Lets play! Woooooo. I love bang/buck stuff. So I'm gonna try to do this right.
We'll start with a chart grabbed from
this fine article which Toms Hardware put together at the end of 2003.

Now, this is a bit out dated. For example the new 6800 series from NVidia and the X800 series from ATI both rock everything on this chart -- and they cost about a years wages for the average iraqi. But the chart contains everything we're interested in.
I want to focus on the middle section; thats where most of the best deals will be found. (80% of the performance / 50% of the cost. You know the drill.)
Now, starting with the GeForce FX 5700, there's
one at newegg for $139 that gets alot of very good reviews. You'll like this one Wpns, cause it has 2 cooling fans and looks all pretty.
Theres also a fairly well reviewed
ATI Radeon 9600XT at newegg for $159, which makes sense since your getting slightly better performance from that card (at least in this specfic benchmark).
Now these are both reasonably priced, and deliver good performance. (I'd just like to note that my Ti 4400 is on that chart, and even though it's a 4th generation card, and getting long in the tooth, its still only 21FPS slower (about 16%) than the GeForce FX5700, which occupies a similar rank in its 5th generation family. Thats what I'm saying about the FX cards, Elvis. NVidia dropped the ball. Not that ATI is much better, mind you -- they merely caught up.)
At the upper end, you dont see alot of the FX 5800 series, and a FX5900 series GeForce or a Radeon 9800 series will cost you about $100 more than the cards mentioned above. So it seems like the 5700 / 9600 is the right mark. Make sure you get the 5700 or the 5700 Ultra in GeForce, or the 9600 XT in ATI, since these are the better performers.
For me, I can only
dream.